T-shirt   Code 112

First things first, and just in case, shirts are mainly long-sleeved compared to T-shirts' short sleeves. That said, you do of course get short sleeved shirts in which case the main difference with T-shirts is the collar and front opening with buttons. Shirts are worn to more formal occasions.
A polo shirt, tennis shirt, golf shirt, or chukker shirt is a form of shirt with a collar. Polo shirts are usually short sleeved but can be long; they were used by polo players originally in India in 1859 and in Great Britain during the 1920s.
There are many different types of shirt collars. Still, the most common is the spread collar, the mandarin/band collar, the button-down collar, the Cuban collar, the cutaway collar, the hoodie collar, the club collar, and the point collar.